Steel pipelines are widely used to carry hydrocarbons though the sea. Such a pipeline includes multiple steel pipe sections, each of a length such as 40 feet (12.2 meters) for pipe sections having a ten inch (0.254 m) diameter, with adjacent ends that are connected together. Many different techniques are used to connect adjacent ends together. One method is thermal expansion-shrinking where one pipe end is expanded with heat and the other one is shrunk with cold before interfitting them. Another is a braze coupling where brazing material (but not the pipe ends) is melted to join two pipe ends. Another is mechanical upsetting in which one pipe end is forcefully expanded to receive the other. Another is a castellated or ordinary thread coupling where a separate coupling with female threads threadably joins two male-threaded pipe ends. Another is forming concentric grooves on threads in pipe section ends that are axially forced together without screwing. Another is a direct threaded coupling where threaded male and female pipe ends are coupled by direct threading to each other. In most of these connecting methods, the pipe ends must be securely gripped, or clamped by tools that can move the pipe ends together and possibly turn one and prevent turning of the other.
Steel pipelines that lie in the sea and carry hydrocarbons are almost always coated with a protective coating. The coating protects the pipeline from corrosion caused by seawater. The coating is usually necessary also, to prevent excess cooling of hydrocarbons in the pipeline, which could result in the forming of wax or hydrates in the pipeline that could block it.
It is usually desirable to apply pipe section coatings on land, where the most reliable coatings can be applied, and at lowest cost. However, coatings applied to surfaces that must be gripped by tools such as jaws, will often be damaged by the tools. Also, the tools often will not achieve a good grip on the relatively soft surfaces of coatings as compared to the steel surface of the pipe itself. A method that allowed the connection of pipe sections in a manner that provided steel pipe grip surfaces for engagement by pipe-gripping tools, while requiring a minimum of coating operations during in-field offshore operations, would be of value.